[time-nuts] Maxim DS1342

paul swed paulswedb at gmail.com
Mon Nov 11 20:45:43 EST 2013


Because the 32Khz xtals are profoundly cheap and accurate to some extent.
Long divide by 2 chain is very simple. The xtal could be easily adjusted
close to the correct frequency. It all sort of came from watch technology.
Regards
Paul
WB8TSL


On Mon, Nov 11, 2013 at 8:06 PM, Russ Ramirez <russ.ramirez at gmail.com>wrote:

> Hi Didier,
>
> True this could be done in SW, and I should have mentioned that I
> considered that in my post. However, these chips offer several other
> functions that would add complexity to the code, and I've been looking for
> a reason to do a simple HW project and open source it through OSH Park
> anyway. I'm not looking to do this for just myself.
>
> Looking across the TI and Microchip lines a bit, it strikes me as odd that
> more micros supporting integrated RTCs actually use two I/Os for a 32 kHz
> crystal option. Why they support an RTC is not mysterious at all, but why
> not the option at to drive the 1 Hz clock directly rather than dividing 32
> kHz down to 1 Hz and using an extra I/O is odd when these I/Os are usually
> configurable anyway.
>
> Russ
>
>
> You want to drive the RTC with an external PPS to get time/date into an
> > Arduino?
> > Why not feed the PPS to the Arduino and have it compute date and time?
> >
> > It is really not that hard to count seconds. You don't really need an
> > external chip to do that.
> >
> > Didier KO4BB
> >
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